A bottle containing 40 fluid ounces of malt liquor beer. The beer is of low quality and fairly cheap to buy. A bottle can run you usually between 2 and three dollars depending on brand. 40's are popular in a variety of areas and are drunken by many types of people. Gangstas will drink 40's and will sometimes pour out a little of the beer onto the ground for their dead homies. Teenagers also like to drink 40's because it is a fast way to get drunk and all the beer is in one bottle opposed to drinking several smaller 12 ounce bottles and/or cans. Some brands of beer produced in the 40 ounce variety are Clot 45, Olde English, Mickey's, and King Cobra.